The present invention relates in general to inking systems and in particular to a new and useful spiral-type ductor for transferring ink from a fountain roller to a roller for taking up the ink along a spirally extending line using a plurality of eccentrically moving elastic rings.
A spiral-type ductor is known from German AS No. 12 40 889. In that design, all the eccentrics are driven uniformly. The rings which are supported for free rotation on the eccentrics are usually coated with an elastic material which, according to experience and with a full setting against the metal surface of an inking roller, is being radially squeezed to a depth of 0.3 mm. This results in a mutual contact through an angular zone of the eccentric of about 50.degree. to 60.degree..
Since, of course, an individual ring cannot transfer more than the ink amount taken up from the inking roller during the contact period, very narrow limits are set to the application of this design in practice, since high paper speeds are required entailing a high ink consumption, and neither the thickness of the ink film nor the speed of the inking roller or the degree of setting of the ductor roller can be increased at will without losing control over the entire inking system.